The proposed project is to investigate the physical structure of corneal scar tissue and biological influences on its synthesis. Using characteristic biosynthetic patterns of corneal proteoglycans as an assay for scar tissue formation, biochemical aspects of the cellular environment which are responsible for the maintenance of keratocyte differentiation will be assessed in vitro. Factors which induce the formation of wound healing fibroblasts from keratocytes will also be characterized. Changes in the levels of biosynthetic enzymes of glycosaminoglycans will be measured in normal keratocytes and after induction of the wound healing reaction. Pool levels of glycosaminoglycan UDP-sugar precursors and the epimerases which control these levels will also be examined. The physical relationship of proteoglycan to stromal structure will first be examined by exploring aspects of proteoglycan structure. The number and heterogeneity of proteoglycans in the stroma will be examined by investigating the number of protein core molecular species and determining the distribution of GAG types on these cores. The chemical nature of the association of proteoglycan with collagen will also be investigated. Study of the agents needed to dissociate proteoglycan from collagen fragments will help define the chemical nature and location of the bond between these compounds. Electron microscopy of the stroma of normal and wounded corneas will also be used to study the proteoglycan-collagen structural relationship. Specific degradative enzymes will be used to pre-treat stroma for identification of the GAG types involved in the corneal collagen-proteoglycan interaction.